The proposed research will utilize the chronically instrumentetized sheep lung model to study the effects of acute and chronic alterations of pulmonary microvascular hydrostatic pressure and plasma oncotic pressure on the other Starling forces for both normal and increased permeabliliy condtions. This will enable me to quantitate the relative contributions of the pulmonary edema safety-factors. By utilizing the techniques of maximal lymph protein washdown to estimate the oncotic and solvent-drag reflection coefficients, a critical evaluation will be made of the pulmonary permeability characteristics for normal and increased permeability conditions. Moreover, the excluded interstitial volume for albumin will be measured along with the electrostatic charge potential of the pulmonary microvascular membrane will be determined by measuring the lymph to plasma ratio of the five lactate dehydrogenase isozymes.